Class: Empirical::SignatureProcessor

Inherits:
BaseProcessor show all
Defined in:
lib/empirical/signature_processor.rb

Constant Summary

Constants inherited from BaseProcessor

BaseProcessor::EVAL_METHODS

Instance Method Summary collapse

Constructor Details

#initialize ⇒ SignatureProcessor

Returns a new instance of SignatureProcessor.



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# File 'lib/empirical/signature_processor.rb', line 4

def initialize(...)
	@return_type = nil
	@block_stack = []
	super
end

Instance Method Details

#visit_call_node(node) ⇒ Object 



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# File 'lib/empirical/signature_processor.rb', line 10

def visit_call_node(node)
	case node
	in { name: :fun }
		original_return_type = @return_type
		@return_type = visit_fun_call_node(node)
		super # ensures any early returns are processed (also, technically, any internal method defs)
		@return_type = original_return_type

	# handle "method macros" (like `private`, `protected`, etc.)
	# because the body block is attached to that call node,
	# not the `fun` call node
	in { block: Prism::BlockNode }
		@block_stack << node.block
		super
		@block_stack.pop
	else
		original_return_type = @return_type
		super # ensures any early returns are processed (also, technically, any internal method defs)
		@return_type = original_return_type
	end
end

#visit_fun_call_node(node) ⇒ Object

Raises:

  • (SyntaxError) 


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# File 'lib/empirical/signature_processor.rb', line 32

def visit_fun_call_node(node)
	# TODO: better error messages
	raise SyntaxError unless node.arguments
	raise SyntaxError unless nil == node.receiver

	case node
	in {
		arguments: Prism::ArgumentsNode[
			arguments: [
				Prism::KeywordHashNode[
					elements: [
						Prism::AssocNode[
							key: signature,
							value: return_type
						]
					]
				]
			]
		]
	}
		body_block = node.block || @block_stack.first
		preamble = []
		postamble = []

		case signature
		# parameterless method defs (e.g. `fun foo` or `fun foo()`)
		in Prism::LocalVariableReadNode | Prism::ConstantReadNode
		# no-op
		# parameterful method defs (e.g. `fun foo(a: Type)` or `fun foo(a = Type)`)
		in Prism::CallNode
			raise SyntaxError if signature.block

			signature.arguments&.arguments&.each do |argument|
				case argument
				# Positional splat (e.g. `a = [Type]` becomes `*a`)
				in Prism::LocalVariableWriteNode[name: name, value: Prism::ArrayNode[elements: [type]]]
					# make argument a splat
					@annotations << [
						argument.name_loc.start_offset,
						0,
						"*",
					]

					# remove the type and equals operator from the argument
					@annotations << [
						argument.name_loc.end_offset,
						type.location.end_offset - argument.name_loc.end_offset + 1,
						"",
					]

					preamble << "raise(::Empirical::TypeError.argument_type_error(name: '#{name}', value: #{name}, expected: ::Literal::_Array(#{type.slice}), method_name: __method__, context: self)) unless ::Literal::_Array(#{type.slice}) === #{name}"

				# Positional (e.g. `a = Type` becomes `a = nil` or `a = default`)
				in Prism::LocalVariableWriteNode[name: name, value: typed_param]
					case typed_param
					# Positional with default (e.g. `a = Type | 1` becomes `a = 1`)
					in Prism::CallNode[name: :|, receiver: type, arguments: Prism::ArgumentsNode[arguments: [default]]]
						type_slice = type.slice
						default_string = default.slice
					# Positional without default (e.g. `a = Type` becomes `a = nil`)
					else
						type_slice = typed_param.slice
						default_string = "nil"
					end

					# replace the typed_param from the argument with the appropriate default value
					@annotations << [
						(start = typed_param.location.start_offset),
						typed_param.location.end_offset - start,
						default_string,
					]

					preamble << "raise(::Empirical::TypeError.argument_type_error(name: '#{name}', value: #{name}, expected: #{type_slice}, method_name: __method__, context: self)) unless #{type_slice} === #{name}"

				# Keyword (e.g. `a: Type` becomes `a: nil` or `a: default`)
				in Prism::KeywordHashNode
					argument.elements.each do |argument|
						name = argument.key.unescaped

						nilable = false

						if name.end_with?("?")
							name = name[0..-2]
							nilable = true

							@annotations << [
								argument.key.location.end_offset - 2,
								1,
								"",
							]
						end

						typed_param = argument.value

						case typed_param
						# Keyword splat (e.g. `a: {Type => Type}` becomes `**a`)
						in Prism::HashNode[elements: [Prism::AssocNode[key: key_type, value: value_type]]]
							# make argument a splat
							@annotations << [
								argument.key.location.start_offset,
								0,
								"**",
							]

							# remove the typed_param and equals operator from the argument
							@annotations << [
								argument.key.location.end_offset - 1,
								typed_param.location.end_offset - argument.key.location.end_offset + 1,
								"",
							]

							preamble << "raise(::Empirical::TypeError.argument_type_error(name: '#{name}', value: #{name}, expected: ::Literal::_Hash(#{key_type.slice}, #{value_type.slice}), method_name: __method__, context: self)) unless ::Literal::_Hash(#{key_type.slice}, #{value_type.slice}) === #{name}"
						else
							case typed_param
							# Keyword with default
							in Prism::CallNode[name: :|, receiver: type, arguments: Prism::ArgumentsNode[arguments: [default]]]
								type_slice = if nilable
									"::Literal::_Nilable(#{type.slice})"
								else
									type.slice
								end

								default_string = default.slice
							else
								type_slice = if nilable
									"::Literal::_Nilable(#{typed_param.slice})"
								else
									typed_param.slice
								end

								default_string = "nil"
							end

							# replace the typed_param from the argument with the appropriate default value
							@annotations << [
								(start = typed_param.location.start_offset),
								typed_param.location.end_offset - start,
								default_string,
							]

							preamble << "raise(::Empirical::TypeError.argument_type_error(name: '#{name}', value: #{name}, expected: #{type_slice}, method_name: __method__, context: self)) unless #{type_slice} === #{name}"
						end
					end
				else
					# TODO: better error message
					raise SyntaxError
				end
			end
		else
			# TODO: better error message
			raise SyntaxError
		end

		preamble << "__literally_returns__ = ("
		postamble << ")"

		case return_type
		in Prism::LocalVariableReadNode[name: :void] | Prism::CallNode[name: :void, receiver: nil, block: nil, arguments: nil]
			postamble << "::Empirical::Void"
		in Prism::LocalVariableReadNode[name: :never] | Prism::CallNode[name: :never, receiver: nil, block: nil, arguments: nil]
			postamble << "raise(::Empirical::NeverError.new)"
		else
			postamble << "raise(::Empirical::TypeError.return_type_error(value: __literally_returns__, expected: #{return_type.slice}, method_name: __method__, context: self)) unless #{return_type.slice} === __literally_returns__"
			postamble << "__literally_returns__"
		end

		# Replace `fun` with `def`
		@annotations << [
			(start = node.message_loc.start_offset),
			node.message_loc.end_offset - start,
			"def",
		]

		# Remove the return type and `do` and replace with preamble
		@annotations << [
			(start = signature.location.end_offset),
			body_block.opening_loc.end_offset - start,
			";#{preamble.join(';')};",
		]

		# Insert postamble
		@annotations << [
			body_block.closing_loc.start_offset,
			0,
			";#{postamble.join(';')};",
		]
	else
		# TODO: better error message
		raise SyntaxError
	end

	return_type
end

#visit_return_node(node) ⇒ Object 



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# File 'lib/empirical/signature_processor.rb', line 226

def visit_return_node(node)
	case @return_type
	in nil
		# no-op
	in Prism::LocalVariableReadNode[name: :void] | Prism::CallNode[name: :void, receiver: nil, block: nil, arguments: nil]
		if node.arguments
			raise "You’re returning something"
		else
			@annotations << [
				node.keyword_loc.end_offset,
				0,
				"(::Empirical::Void)",
			]
		end
	in Prism::LocalVariableReadNode[name: :never] | Prism::CallNode[name: :never, receiver: nil, block: nil, arguments: nil]
		@annotations << [
			node.keyword_loc.start_offset,
			node.keyword_loc.end_offset - node.keyword_loc.start_offset,
			"(raise(::Empirical::NeverError.new))",
		]
	else
		@annotations.push(
			[
				node.keyword_loc.start_offset,
				node.keyword_loc.end_offset - node.keyword_loc.start_offset,
				"(__literally_returning__ = (",
			],
			[
				node.location.end_offset,
				0,
				");(raise ::Empirical::TypeError.return_type_error(value: __literally_returning__, expected: #{@return_type.slice}, method_name: __method__, context: self) unless #{@return_type.slice} === __literally_returning__);return(__literally_returning__))",
			]
		)
	end

	super
end